Combination tool



Oct. 19, 1943.

J. K, MCMASTER COMBINATION TOOL Filed Nov. 4,1942

Llamas KlM Master Patented Oct. 19, 1943 UNITED STATES EATENT GFFMZE COMBINATION TQGL James K. McMaster, Springfield, Mass.

Application November 4t, 1942; Serial No. 464,503

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 G. 757) 1 Claim.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a combination tool for disassembling and assembling a machine gun firing pin spring.

Disassembly of the firing pin spring from the firing pin of a firearm, particularly machine guns, without the aid of some tool is a rather difiicult and hazardous operation. This is because the firing pin spring is generally retained within the hollow body of the firing pin by a retaining pin and is at all times under considerable compression. Upon removal of the retaining pin the firing pin spring will fly outwardly with considerable force due to the compressed state of the spring. Unless this spring is in some manner restrained from flying out of the firing pin bodily injury may result to any bystander.

Assembly of the spring to the firin pin is likewise a hazardous difficult procedure. As the spring is a very stiir one considerable force is required to compress it sufiiciently to enable the retaining pin to be inserted in the retaining pin hole in the firing pin. Special fixtures have been devised to facilitate the assembly of this spring but these fixtures were cumbersome and expensive to make. Due to the large, awkward size of these fixtures they were entirely unsuitable for general use in machine gun repair work. Therefore a small compact tool which is convenient to transport and use is most desirable.

Accordingly it is an object of this invention to provide acombination tool for the disassembly and assembly of a firearm firing pin spring.

Another object of this invention is to provide a firing pin disassembly and assembly tool for a machine gun such a disclosed in U. S. Patent No. 1,293,021 to John M. Browning.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. l is a side elevational View of the combination tool shown in the extended position.

Fig. 2 is a view similar to that shown in Fig. l but with the tool in the closed position.

Fig. 3 is a View showing the combination tool in position for disassembling the firing pin spring of a firing pin.

Fig. 4 is a cross-sectional view taken along the plane 44 of Fig. 1.

Fig. 5 is a right end elevational view of Fig.1.

In Fig. 1 there is shown in assembled relation a combination tool for the disassembly and assembly of a firing pin spring of a machine gun firing pin. A firing pin support l is provided to support a firing pin 5 while disassembling a firing pin spring 6. The support I comprises a comparatively long, tubular body 1 having one end 8 of enlarged diameter. A cone-shaped section 9 connects the body 1 and the enlarged end 8 of the support 1. A transverse U-shaped. notch I8 is provided across the bottom of the enlarged portion 8 of the support I. The interior of the enlarged portion 8 is shaped to receive the forward end ll of a firing pin 5 as shown in Figure 3. An axial slot I2 is provided in the body portion 1 of the support I. The slot I2 is cut through both walls of the body portion 1 and is cut on the same axis as the transverse notch Ii]. Slot I2 starts somewhat below the end of the body portion 1 and extends to the juncture of the body 7 and the conical section 9.

A plunger 2 is inserted within the tubular body 1. The end It of the plunger 2 within the body I is bifurcated. Attached to the other end of the plunger 2 is a conventional wooden handle 3 provided with a metal ferrule to prevent splitting of the wooden portion of the handle. The handle 3 is secured to the plunger 2 by a pin It. The plunger 2 is of such length that when the plunger is fully inserted within the tubular body 1 the bifurcated end l3 of the plunger 2 will project somewhat beyond the end of the enlarged portion 8 as shown in Fig. 2. The plunger 2 is slidably secured within the body 'I by a pin t in such a manner that the slot formed by the bifurcated end l3 of the plunger 2 will be in alignment with the slot H2. The pin 4 is driven into a suitable hole in the plunger 2 and permits longitudinal movement of the plunger 2 within the support 1 by an amount equivalent to the length of slot l2. The pin 4 projects an equivalent amount from each side of plunger 2 as far as the outside diameter as the body I in order to provide a suitable stop as the plunger 2 is moved within the body portion 1.

Referring to Fig. 3 to remove firing pin spring 5 from the firing pin 5, the rear end I5 of firing pin 5 is preferably held in a vise or it may be placed against a suitable stop. The enlarged portion 8 of support I is then placed over forward end ll of firing pin 5. The firing pin spring 6 is retained within firing pin 5 by a pin IS. The notch H! on the end of the enlarged portion 8 is placed about pin it. The plunger 2 is then thrust inwardly so that the bifurcated end l3 of plunger 2 straddles pin I6 and engages the end of the firing pin spring 6. The continued pressure on handle 3 compresses firing pin spring 6 sufficiently so that it no longer bears against pin IS. The pin I5 is then removed with a suitable drift and plunger 2 is slowly Withdrawn. This movement releases the compression in spring 6 and as spring 6 is no longer retained by pin I6 the spring is then readily removed and without any danger of injury to the user. Assembly of the firing pin spring is readily accomplished by reversing the procedure described above for the disassembly of the spring.

It is readily apparent that the tool described compressed spring must be inserted behind a transverse pin.

I claim:

A tool for assembling a compressed spring behind a transverse pin in a firing pin comprising a cylindrical body teminating in a pair of prongs, said prongs constructed to straddle the transverse pin and engage the compressed spring within a firing pin, a' sleeve surrounding said cylindrical body, a projection on said cylindrical body, a longitudinal slot in said sleeve cooperating with said projection to limit the movement of the sleeve on the cylindrical body and a hollow head on said sleeve member constructed to enis not limited in application to firing pins but 15 gage the front end of a firing pin.

may be used for assembly or disassembly of a spring in any type of spring holder where the JAMES K. MCMASTER. 

